Numerical Investigation of Film Cooling Effectiveness and Flow Field Characteristics over a Flat Plate with in-Hole Swirl Generator

Abstract

The performance of a new film cooling scheme has been numerically investigated. The scheme consists of a blade-type swirl generator that adds a swirl pattern to the injected coolant stream. Reynolds-Averaged Navier-Stokes equations along with a realizable k-ε turbulence model have been solved. The film cooling effectiveness over a flat plate downstream the coolant injection hole was determined for different generator geometric parameters and operating conditions. These parameters are the generator length to the injection hole diameter ratio, twist angle, and location from the hole inlet. The operating conditions are four different blowing ratios, constant density ratio of 2.0, mainstream turbulence intensity of 5% and Reynolds number of 80,000 based on the hole diameter and mainstream velocity. The results showed an enhancement in the laterally averaged cooling effectiveness accompanied by enriched jet spreading downstream the in-hole swirl generator, while the area-averaged cooling effectiveness increased by 74%, 293%, and 805% at blowing ratios 1.0, 1.5 and 2.0, respectively, compared to that for a scheme without swirl generator. Such enhancement is attributed to the vortical structure generated and hence the interaction with the mainstream. Optimization was carried out on obtained results to determine the optimal swirl generator geometric parameters.

Keywords

• film cooling
• swirling coolant flow
• crvp
• vortex reconstruction
• blade-type swirl generator